Quote:
Originally Posted by BroadHopper
I was driving the ol' Jeep down 89 from Burlington VT Friday. It was fairly straight stretch in Andover, NH. With the cruise control set at 74 on my Garmin NUVI 225, the Jeep speedometer says 77,78 mph. Local Andover cruiser stopped me and clocked me at 82 mph! So the GPS was off 8 mph!
Garmin claims .1 mph accuracy. I was traveling in a straight line. I'm wondering if the radar could be inaccurate. It was an one of those dashboard mounted units and he was parked in the median.
I wonder how they check the accuracy of police radar as I am sceptical of an 8 mph difference. How would you know if the LEO is telling the truth?
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BH, not sure if you had other cars around but if you are doing 75-78 MPH that seems to be about the flow of traffic. Once you hit the 80+ MPH point is when you are basically passing most cars on the road. Kinda of a crude way to look at it.
As far as my Garmin GPS (Nuvi 2xx series), it seems to match quite well to my speedometer in all my vehicles. But I also run OEM tires.
Does your vehicle has the STOCK tire sizes and STOCK rear gears? Change either one of those and your speedometer (or speed sensor gear) will require changing. Changing from say a 255 to a 265 tires and or vice versa and you can get a different reading. There's converter tables out there to tell you the different speedometer readings.
Changing to a smaller tire is a cheating way to get more gearing in your rear-end (well, your vehicles anyway)......